The present invention is directed to an expansion dowel including an axially extending expansion sleeve partially slit in the axial direction. The sleeve is formed of sheet metal and has an internal thread extending from the trailing end of the sleeve toward the leading end. The sleeve forms an axially extending bore or opening which is conically shaped from the leading end toward the trailing end for at least a portion of the sleeve. The conically shaped portion has axially extending projections protruding radially outwardly from the outside surface of the conically shaped portion. The projections are stamped outwardly from the sleeve.
Plastic dowels are often used as secondary fasteners. Such plastic dowels have the disadvantage that the fastening fails in the event of fire. As a result, simple dowels formed of sheet metal have replaced plastic dowels to a great extent.
Sheet metal dowels, such as disclosed in GB-PS 569 774, are formed of a rolled expansion sleeve with a screw thread for a fastening screw. To expand the sleeve in such known dowels, the sleeve forms an axially extending bore or opening which converges conically toward the leading end and has projections stamped outwardly in the sleeve.
From the viewpoint of production, these known dowels have the advantage of great economy, however, from the viewpoint of application they have the disadvantage that the anchoring values drop sharply if the borehole formed in the receiving material for the dowel is too large or if the receiving material is excessively soft.